In order properly to study many health-related problems it is necessary to understand how enzymes work. One of the best tools for doing this is kinetics, since in a kinetic study one looks at the reaction while it is taking place. Experience has shown that there are three levels of kinetic study of an enzyme. First, one establishes the kinetic mechanism, which is a description of the order in which reactants add to and products leave the enzyme. Second, one establishes the relative rates of the various steps in the kinetic mechanism. Finally, one attempts to deduce the actual chemical steps that occur on the enzyme. The purpose of this project is to develop kinetic tools for carrying out the various steps in analysis of the kinetic and chemical mechanism of enzymes, and to apply these tools to specific enzymes. Excellent progress towards these goals has been made, but all indications are that considerable development is still possible in the theoretical techniques, and of course, the number of enzymes whose kinetic and chemical mechanisms are well worked out is still small.